1. Field of the Invention
The invention relates to an image processing system for generating at least one output image related to an input image through a parallactic transformation; the image processing system comprising input means, output means, a memory and a processor; the input means comprising means for receiving a respective input pixel value and input pixel depth of input pixels of the input image and for storing received input pixel values in the memory; the processor being operative to create output pixels of the output image by deriving for the output pixel a respective output pixel value from the input pixel value of at least one input pixel, which is parallactically related to the output pixel; the parallactic relationship being a function of the respective input pixel depth; the output means comprising means for outputting the output pixel values.
The invention further relates to a processor for parallactically transforming an input image into at least one output image; the processor comprising an input for receiving a respective input pixel value of input pixels of the input image and an output for outputting a respective output pixel value for output pixels of the output image; the processor being operative to create the output pixel by deriving a respective output pixel value from the input pixel value of at least one input pixel, which is parallactically related to the output pixel.
2. Description of Related Art
The interest in providing a depth sensation when displaying an image on a 2D display is growing rapidly, notably in virtual reality applications and computer games. Various forms of providing depth cues, such as influencing the brightness level or the size of an object, are known. Particularly, stereopsis, or stereoscopic vision, receives much attention as a technique for providing depth sensation. Stereopsis is evoked by presenting to a person two 2D images of the same scene as observed from two positions a little way apart. One of the images is presented to the left eye, the other one is presented to the right eye. The two images are parallactically related. The term "parallax" refers to the apparent displacement or the difference in apparent direction of an object as seen from two different points not on a straight line with the object. Parallax allows a person to perceive the depth of objects in a scenery.
It is known from U.S. Pat. No. 5,379,369 to generate from one 2D input image separate output images for each of the eyes. In the known system, the 2D input image represents objects observed from a point corresponding to a middle point in between both eyes. The left eye image is a 2D representation of the objects observed from a point corresponding to the visual point of the left eye. The right eye image is a 2D representation of the objects observed from a point corresponding to the visual point of the right eye. Typically, the 2D input image is given in the form of an array of pixels. It may, for instance, have been obtained using a camera or computer graphics. For each of the pixels of the input image additional depth information is available. In the known system, depth information is derived from the 2D input image itself, for instance based on brightness levels of pixels of the 2D input image. Based on the parallax when observing the same object from the visual point of the eyes and from the middle point in between the eyes, the pixels of the left eye image and the right eye image are derived from the pixels of the input image by shifting the pixels. By choosing the horizontal axis of the co-ordinate system as being parallel to the line connecting both eyes, only a horizontal shift occurs. The amount of shift of a pixel depends on the depth information. Typically, a graphical processing system suitable for generating parallactically related images from an input image comprises a memory, such as a graphics memory, for storing the 2D input image with the additional depth information. The 2D input image and the depth information are usually supplied by an application program. Typically, a copy of the 2D input image and the depth information is also stored in a memory for use by an image processing system. The image processing system generates one or more 2D output images from the 2D input image and the depth information. The output images are parallactically related to the input image. The generation is achieved by performing a depth dependent shift of the pixels of the 2D input image. The 2D output images are stored in a graphics memory. Using a D/A converter the 2D output images are displayed using a suitable stereoscopic display system. Many display techniques for displaying stereoscopic images are known. Using a time-parallel technique, both output images are presented simultaneously to one or two displays. For example, both images may be filtered with complementary colours and superimposed on one display. The observer wears glasses with filters that match the projection filters. Alternatively, both images may be displayed alongside on one display and viewed using a viewer which directs each image to the correct eye. As another example, two displays may be used to present two differently polarised pictures, which are viewed through correspondingly polarised glasses. Alternatively, both images may be presented using a head-mounted device with separate displays for each eye. Also time-multiplexed techniques may be used, where the left and right images are alternatingly displayed on one display. As an example, one image is written to the even scan lines of a monitor and the other image to the odd scan lines. A shutter system is used to occlude the left eye when the right-eye image is displayed and to occlude the right eye when the left-eye image is displayed. The shutter system may be mounted in glasses worn by the observer. Alternatively, a shutter with a controllable polariser is placed in front of the display and the observer wears a head-mounted device with polarised glasses.
The known image processing system is relatively costly for use in consumer products, such as game computers and PCs. Moreover, only moderate quality can be achieved.